Lawrence Wilkerson, top aide and later chief of staff to Secretary of State Colin Powell: As my boss [Colin Powell] once said, Bush had a lot of .45-caliber instincts, cowboy instincts. Cheney knew exactly how to polish him and rub him. He knew exactly when to give him a memo or when to do this or when to do that and exactly the word choice to use to get him really excited.

from vanity fair's oral history of the bush white house. it's long, but worth reading in its entirety.